Write a personal code of relationship virtues. Aim for language that is powerful and motivating, that makes sense to your head and touches your heart. It doesn't have to be perfect to be useful and you can always revise it later.
It may look like this:
My Personal Code
Listen more, talk less.
Don't yell at my partner or don't let him/her do that to me.
Everyday, ask my partner three questions in a row about how things are going for him/her.
Get home by six every night to have dinner with my partner.
Keep my promises.
When you are finished writing a personal code, visualize yourself acting according to your code no matter what happens. Imagine the good feelings and other rewards that this will bring you.
Take it in to help motivate yourself to truly live by your code. Then, when you do live by it, and things go well, take that in too.